Antonios Georgelis

The human toxicological risk assessment of per- and polyfluoroalkyl substances (PFAS) is challenging, due to their sheer number and structural diversity, but also the paucity of the toxicity data required to characterize them. The development of Next Generation Physiologically Based Kinetic (NG-PBK) models may assist in overcoming this challenge. The mechanistic nature of NG-PBK models allows for their extrapolation from data-rich PFAS, such as perfluorooctanoic acid (PFOA), to data-poor ones, facilitating their application in Next Generation Risk Assessment (NGRA). The present study proposes a NG-PBK model for PFOA in humans, parametrized exclusively using in vitro-, and in silico-derived data. The model describes the toxicokinetic processes of 1) partitioning to plasma and tissue proteins, 2) partitioning to cell membrane lipids, 3a) transporter-mediated entero-hepatic circulation and 3b) renal elimination and reabsorption, and 4) elimination via menstruation. Global sensitivity analysis indicated that the model was most sensitive to the fraction unbound in plasma, active-transport parameters, and tissue-plasma partition coefficients. The model was equivalent to already available validated human PFOA-PBK models, while compared to those, it is not calibrated to observed animal, nor human data, illustrating its strength in being mechanistic. The serum concentrations and half-lives predicted by the NG-PBK model were within the ranges of those reported in human volunteer and biomonitoring (HBM) studies, demonstrating the model’s capacity to accurately predict PFOA toxicokinetics on exposure estimates. Extrapolation of the NG-PBK model to other PFAS, in conjunction with its integration with HBM data, will facilitate the NGRA of PFAS. This is particularly relevant given the paucity of in vivo data for most PFAS, ensuring compliance with the 3R principles.

Objectives The aim of this study was to analyse associations between crowded housing and children’s indoor living environment, respiratory and allergic disorders and general health. Design A cross-sectional study. Setting Sweden, using data from the Swedish National Environmental Health Survey 2019. Participants The study sample included 48 512 children (aged 6–10 months, 4 years and 12 years). We also investigated associations in vulnerable subgroups, such as children with asthma and those living under unfavourable socioeconomic conditions. Primary and secondary outcome measures Primary outcomes in the living environment were at least one sign of mould, poor indoor air quality, unpleasant odours, too warm indoors in summer and too cold indoors in winter. Primary outcomes for children’s health were asthma, airway problems, breathing difficulties, rhinitis symptoms, mould and mites allergy, pollen allergy, furred pet allergy and good general health. Results About one in five children lived in an overcrowded home. Factors from the indoor living environment such as perceived poor indoor air quality and mould were significantly associated with crowded housing. Moreover, children who lived in overcrowded conditions were less likely to report good general health than children in non-crowded households (OR 0.64, 95% CI 0.54 to 0.76). This association was even stronger in children with asthma (OR 0.51, 95% CI 0.34 to 0.77). Few significant associations were, however, observed with the respiratory and allergic health outcomes. Conclusions Crowded housing is associated both with a poor indoor environment and with poorer general health in children. Children with asthma may experience even poorer general health.

Background: Allergic rhinitis (AR) is one of the most common chronic diseases worldwide. There are limited prospective long‐term data regarding persistency and remission of AR. The objective of this study was to investigate the natural course of pollen‐induced AR (pollen‐AR) over 20 years, from childhood into early adulthood.Methods: Data from 1137 subjects in the Barn/Children Allergi/Allergy Milieu Stockholm Epidemiologic birth cohort (BAMSE) with a completed questionnaire regarding symptoms, asthma, treatment with allergen immunotherapy (AIT) and results of allergen‐specific IgE for inhalant allergens at 4, 8, 16 and 24 years were analyzed. Pollen‐AR was defined as sneezing, runny, itchy or blocked nose; and itchy or watery eyes when exposed to birch and/or grass pollen in combination with allergen‐specific IgE ≥0.35kU_A/L to birch and/or grass.Results: Approximately 75% of children with pollen‐AR at 4 or 8 years had persistent disease up to 24 years, and 30% developed asthma. The probability of persistency was high already at low levels of pollen‐specific IgE. The highest rate of remission from pollen‐AR was seen between 16 and 24 years (21.5%); however, the majority remained sensitized. This period was also when pollen‐specific IgE‐levels stopped increasing and the average estimated annual incidence of pollen‐AR decreased from 1.5% to 0.8% per year.Conclusion: Children with pollen‐AR are at high risk of persistent disease for at least 20 years. Childhood up to adolescence seems to be the most dynamic period of AR progression. Our findings underline the close cross‐sectional and longitudinal relationship between sensitization, AR and asthma.

Aim: To explore how overcrowding affects children’s health, environment and schooling. Methods: A qualitative study was conducted with individual interviews among 20 participants with occupational experience from overcrowded Stockholm areas but diverse in professions, locations and employers. The interviews were recorded, transcribed and analysed with Systematic Text Condensation. Results: Almost all participants expressed that overcrowding has a negative impact on children’s health, environment and schooling – based on perceptions of precarious and different living conditions for children in overcrowded areas, for example, substandard homes, vulnerability, stress, exclusion, limited resources, lack of learning opportunities, gender differences, confinement, shame, insecurity, conflicts, risk of criminality, and bodily impact, both physical and psychological. Conclusions: Our qualitative evidence suggest that overcrowding has a negative impact on children’s health, environment and schooling.

International data suggest that exposure to nature is beneficial for mental health and well-being. The restrictions related to the COVID-19 pandemic have created a setting that allows us to investigate the importance of greenness exposure on mental health during a period of increased isolation and worry. Based on 2060 responses from an online survey in Stockholm County, Sweden, we investigated: (1) whether the COVID-19 pandemic changed peoples’ lifestyle and nature-related habits, and (2) if peoples’ mental health differed depending on their exposure to greenness. Neighborhood greenness levels were quantified by using the average normalized difference vegetation index (NDVI) within 50 m, 100 m, 300 m, and 500 m buffers surrounding the participant’s place of residence. We found that the number of individuals that reported that they visited natural areas “often” was significantly higher during the pandemic than before the pandemic. Higher levels of greenness surrounding one’s location of residence were in general associated with higher mental health/well-being and vitality scores, and less symptoms of depression, anxiety, and perceived and cognitive stress, after adjustments for demographic variables and walkability. In conclusion, the results from the present study provided support to the suggestion that contact with nature may be important for mental health in extreme circumstances.

International data suggests that exposure for nature is beneficial for mental health and well-being. The restrictions related to Covid-19 pandemic have created a setting that allows us to investigate the importance of greenness exposure on mental health during a period of increased isolation and worry. Based on 2060 responses from an online survey in the Stockholm County, Sweden, we investigated: 1) weather the Covid-19 pandemic changed peoples’ life-style and nature-related habits, and 2) if peoples’ mental health differed depending on their exposure to greenness. Neighbourhood greenness levels were quantified by using the average Normalized Difference Vegetation Index (NDVI) within 50m, 100m, 300m, and 500m buffers surrounding the participant’s place of residence. We found that the number of individuals that reported that they visited natural areas “often” was significantly higher during the pandemic than before the pandemic. Higher levels of greenness surrounding one’s location of residence were in general associated with higher mental health/wellbeing and vitality scores, and less symptoms of depression, anxiety, and perceived and cognitive stress, after adjustments for demographic variables and walkability. In conclusion, the results from the present study provided support to the suggestion that contact with nature may be important for mental health in extreme circumstances.

Environmental Health Perspectives is an Open Access journal published by the National Institute of Environmental Health Sciences. Environmental Health Perspectives is an Open Access journal published by the National Institute of Environmental Health Sciences.